The University of Montana, all Missoula County public schools and many other Western Montana campuses were closed after a blizzard warning was issued for an area stretching from Glacier National Park to south of Hamilton.

The National Weather Service said a strong Arctic air mass would move into the state, causing dangerous travel conditions due to blowing and drifting snow and whiteout conditions.

The mercury is expected to dip below zero with wind chills possibly hitting 40 degrees below zero or less. The weather service has issued a winter storm warning for southwestern, central and south-central Montana, with up to a foot of snow forecast in some areas.

Residents of north-central Montana were warned that wind chill temperatures could dip as low as 60 below at times.

School closures were announced Friday, including postponements of many high school and college sporting events.

The Department of Transportation closed U.S. Highway 191 in central Montana between Harlowton and Eddies Corner just after midnight Thursday due to heavy snow and poor visibility, while a section of U.S. Highway 89 from the Kiowa Junction west of Browning to St. Mary was closed due to the weather.

In eastern Montana, traffic was rerouted around a section of Interstate 90 near Columbus Friday morning after several semis stopped and blocked the lanes because of heavy snow and poor visibility. The westbound lanes of Interstate 90 from Reedpoint to Park City also closed for a time Friday morning because semis were stuck on the hill, the DOT said.

A semitrailer slid off Interstate 90 east of Laurel at about 4:30 a.m. Friday, rolling onto its side and hitting a power pole. The Montana Highway Patrol said the driver was not injured.